Publication: Electrical Record
New York, NY, United States
"Plug" Porcelain Knob and "Callender"
This "Plug" porcelain knob is now being offered to the trade by the Illinois Electric Porcelain Co., Macomb, Ill. This knob is 1 3/16 in. in diameter. Code standard, plus. It is designed for use with wires ranging from No. 10 to No 14. This plug will save time in hunting for component parts of wiring fittings, as the base, cap, leather head and nail are all assembled in the one piece.
This company is also marketing a porcelain tube wiring fitting called the "Callender". This tube is supplied with sharp edged projections which cut into the wood when the tubes are driven with a mallet. These edged projections prevent the tube from pulling out when wires are withdrawn or the beams are subjected to heavy vibration.